Abstract 4364: Variability of Distal Left Main Assessment Comparing Intravascular Ultrasound Imaging From Left Anterior Descending vs. Left Circumflex Artery
Background: Using intravascular ultrasound (IVUS) the distal left main coronary artery (LMCA) can be assessed from either the left anterior descending (LAD) or left circumflex (LCX) artery coronary arteries.
Methods: In 73 pts undergoing LMCA evaluation, IVUS was performed from both the LAD and LCX back to the aorto-ostial junction. Pre-intervention distal LMCA minimal lumen areas (MLA) were compared from the 2 imaging runs.
Results: The LMCA-MLA from the LAD pullback measured 6.7±3.1mm2 while the measurement from the LCX pullback was 6.8±3.3mm2. In half of the pts, the LMCA-MLA obtained from the LCX pullback was smaller than from the LAD pullback, and in 8 pts (11.0%) the difference was more than 1mm2. In the other half the LMCA-MLA obtained from the LCX pullback was larger than from the LAD pullback, and in 12 pts (16.4%) the difference was more than 1mm2. The Bland-Altman plots indicated that with increasing LMCA size, the difference between the 2 measurements also increased consistently. However, there was still significant variation even among smaller LMCA lumen area measurements.
Conclusions: To determine the correct LMCA minimum lumen area, imaging from both the LAD and LCX is necessary. Because transducer angulation or eccentric transducer position can artificially increase, but not decrease area measurements, the smaller of the 2 LMCA-MLAs should be used to assess LMCA severity.